Portable blast cleaning machine



July 1,1958 H. HASTRUP El'AL 2,840,955

PORTABLE BLAST CLEANING MACHINE Filed July 13, 1955 5 Sheets-Sheet 1FfG. 2

IN VEN TOR. HERMAN HAS TRIJP R011 F C'., HA5 TR UP ATTORNEY July 1, 1958H. HASTRUP EIAL 2,840,955

PORTABLE BLAST CLEANING MACHINE Filed July 13, 1955 I s Sheets-Sheet 2HERMAN HASTRUP ROLFC'. HASTRUP ATTORNEY y 1953 H. HAsTRuP ETAL 2,840,955

PORTABLE BLAST CLEANING MACHINE 3 Sheets-Sheet 3 Filed July 13, 1955 INVEN TOR. HERMAN HAS TRI/P ROLFC. HASTRUP I} bu FIIIIIVIIA4. mm 7 w ATTORNL'Y United States "POR'IA'BILE= BLAST C-LEATJHIG MACHENE HermanHastrup, 'Kane ohe, Oahu, Territory of Hawaii,

and Rolf C. Hastrup, Torrance, {Iaiiii Application July 13, 1955, SerialNo. 521,719

20.1Claims. (CI. 51-8) This invention relates to abrasive blastingmachines for removing paint, rust'orother coatings from surfaces byapplying thereto a blast stream of abrasive particles. More particularlyit relates to an abrasive blast cleaning machinecf the portable type,and one wherein the spent abrasive and .removeddebn's are .kept withinthe machine so as togive an operation that does not contaminate thesurrounding area with 'dust and debris, and wherein the spent abrasiveis separated from debris for continuous reuse. .By asportable machine ismeant one that is fully complete in itself, all. elementsthereof beingcontained therein, including abrasivecontainer and abrasive supply,blast head, nozzles, separator chamber, interconnecting passageways anddust bag, and, said complete machine being .carried about' by axsingleoperator while said machine'isinoperationwas distinguished from machinesin'which certain-component elements necessary for the operation mustremain stationary.

In U. 8. Patent 2,723,498 issued November 15, 1955,

-to Hastrupet al.,.-there;.-is described a portable blast stituentpartsarenot only light and compact but have such connection andcontinuity-with each other that the complete unit: may be lookedupon asconstituting a tool used for blast cleaning rather-than apiece ofequipment or machinery for that purpose-21 completetunitthe total weightof which, including the abrasive recirculated therein, is less thaneight orv nine pounds.

Another object is to;provide aniniproved control for the blast stream inwhich'the abrasive becomes entrained and for the exhaust streamwhichipulls the spent abrasive and debris away from the surface beingcleaned.

Another objectvis to provide a control whichpermits the automaticshutting off of 'thebl'ast streaminadvance of the stopping of the 'saidexhaust stream, thereby guaranteeing that the suction which exhauststhedebris and spent abrasive from: thesurfacebeing .cleanedxcontinuesmomentarily after the end of 'each blast stream period, with theconsequent assurance of a surface free from grit and debris whenthemachine is lifted from the surface being cleaned.

Another object is .togprovide control means by which the said exhauststream can be operated at the will of the operatorwithout.operation ofthe blast stream, thereby permitting the operator to load the machinewith abrasive by drawing the abrasive into the machine by 2,840,955Fatented July 1, 1958 ice will become obvious from the ensuingdescription and the appended. claims.

The invention is exemplified in the following description andillustratedby way of example in the accompanying drawings, in which:

Fig. 1 is a top plan view of our portable blast cleaning machine.

Fig. 2 is a side elevational view of the machine shown in Fig. 1.

Fig. 3 is a sectional view taken on'line 3-8 of Fig. 2.

Fig. 4 is a sectional view taken on line 4-4 of Fig. 1.

i 5 shows in end'elevational viewa portion of the machine shown in planandside elevations in Figs. 1 and 2.

Fig. 6 is asectional viewof the valve mechanism.

Referring now to the drawings and more particularly to Fig. 4:

A blast head, generally represented by 10, having a blast head housing10', the lower part of which is generally cylindrical in shape, isprovided with an inner shoulder 11 on which is. seated a downwardlyextending blast nozzle 12 held in place against said shoulder by spring13 which presses against screw plug 14, which screws into the top of thesaid housing and which by its removal permits removal and replacementof. said nozzle. A gasket washer 15 seals the said screw plug in theblast head housing. By the seating of said nozzle 12 on said shoulder 11the vertical space in which said spring 13 is positioned and which leadsinto saidnozzle 32 is closed off from the interior of said blast headhousing except for the channel through said nozzle,..said closed-otfspace constituting a nozzle chamber 15. for the receipt of blast air aslater explained. .Eductor. sleeve 16 is positioned in axial alignmentbelow the outlet of blast nozzle '12 with its upper end seatedagainstinner shoulder 17 formed in said blast head housing, the lower end ofsaid eductor sleeve beingseated in the inner rubber coating 18 of hollowblast cone 19, the latter member being cylindrical in shape at its upperend and held in place by thumb screw 29 which is threadedIyJfitted inblast head housing 10'. This permits .the removal of eductor sleeve 16for replacement .if need arises from wear. The outer surface of blastcone 19 is covered with rubber coating 20 providedwith ashoulder 21which seats against the lower end of sleeve 22 extending downwardly fromthat part of blast head housing 18' which surrounds andis spaced apartfrom; blast nozzle 12 and the upper part of eductor sleeve. 16. .Thesaid sleeve 22 together with rubber coated blast conel9, form with theouter wall of blasthead housing 10" an annular passageway 23, sometimesreferred to'hereinafter as the outer channel in said blast head It).Similarly the passageway through theeductorsleeve l6 and blast cone19'is sometimes hereinafter referred. to as the inner channel in saidblast head 10. A rubber coating on the inner surface of said housingsupplements rubber coating 20' to provide rubber surface for saidannular passageway. Cylindrical rubber member 25, secured to the lowerend of housing Iii) by means of a groove and lip thereon adapted to snapover ai'mating shoulder 26 on said housing, extends downwardly a shortdistance beyond the end of blast cone 19 and is formed into a surfacecontacting boot adapted to conta'ct'the surface to be blasted. Saidmember is preferably reinforced with sleeve 27.made of aluminum'orothersuitable' material and the lower end of said boot is preferably"made of abrasion resistant rubber formed into a suitable mouth-piece'27 adapted to contact the surface to be blasted. 'The said mouth piecemay be modified to contact surfaces of objects of diiferent shapes.

A blast air tube 28 has one end thereof mounted, by

a threaded, or press, or other suitable fit, in a horizontal bore 29 inthe blast head housing, which said bore communicates with the saidnozzle chamber The outer end of said blast air tube is fitted withrubber bushing 29', later referred to again, and is threaded to receivespecial nut 30 provided with an inner circumferential shoulder 31beveled on one side to fit against a corresponding bevel on the end ofsaid blast air tube. Barbed hose insert 32, provided with an outercircumferential shoulder 33, has one end inserted within nut 36. AnO-ring 34 positioned between shoulders 31 and 33 provides a seal. Aretaining washer 35 fitted around hose insert 32 and against shoulder 33is held in place by the crimped over end of nut 30. Thus, since the hoseinsert 32 is restrained only against being pulled axially out of the nut30, the said nut 30 carried by blast air tube 28 will swivel withrespect to hose insert 32, or vice versa. In other words, since theblast air tube 29 is rigidly fitted to the blast head housing '10 at thebore 29 as aforesaid, when said blast head is rotated, as laterexplained, the said blast air tube 28 will rotate with said blast headand simultaneously will swivel within said nut 30, said nut being heldrigid as later explained. Compressed air hose 36 is slipped over barbedhose insert 32 and is held thereon by clamping ferrule 37.

The blast head housing 10' is formed with an inner laterally extendingcasing or sleeve 38 positioned about and apart from the inner endportion of blast air tube 28, so as to provide an annular passageway 39about said blast air tube, said passageway 39 being in opencommunication with the space or chamber surrounding the lower end ofblast nozzle 12 leading into the mouth of blast eductor sleeve 16 intowhich said blast nozzle discharges. An abrasive hose 40, furtherreferred to later, fits, preferably swivelable, over the end of sleeve38 and thereby lengthens the annular space 39 about blast air tube 28.The blast head housing 10' is further formed into an outer,laterally-extending casing 40 spaced outwardly of and apart from saidinner casing or sleeve 38,

terminating circumferentially and forming with said inner sleeve 38 andsaid abrasive hose 40 a second and outer annular space 41 with respectto said blast air pipe 28, said outer space 41 being in communicationwith the aforesaid annular passageway 23, i. e., the said outer channelin said blast head 10.

Separator housing 42 (see Figs. 1 and 2), enclosing a separator chamber48 (Fig. 2) is formed with an outer, laterally-extending,circumferentially terminating casing 42 which is adapted to mate withthe aforesaid laterally extending casing 40' of the said blast headhousing and is rotatably connected therewith and sealed with O-ring 44(Fig. 4). An inner sleeve casing 43 (Fig. 4) adapted to serve as thecomplement to the aforesaid inner sleeve casing 38 of blast head housing10, projects from separator housing 42 forming an annular space with thesaid laterally extending casing 42, said annular space being incommunication with the said separator chamber 48 generally enclosed bysaid separator housing 42. T he end of said inner sleeve casing 43 isswivelably fitted in the aforesaid abrasive hose 40. While the abrasivetube 40 fits snugly over both inner sleeve casing 43 and inner sleevecasing 38, it may befitted to rotate with respect to either or both ofthese casings. If desired, the sleeve casings 38 and 43 may besuificiently long to be directly rotatably connected together at theirend portions without the use of connecting abrasive tube 40. Theaforesaid mated and rotatably connected casings 4t) and 42 are heldfirmly together by means of a suitable shoulder extending radiallyoutward on the rubber bushing 29 which as hereinabove explained fitsover blast air tube 28 and against which the threaded nut 30 fits. Itwill be observed that annular space 39 dead ends against bushing 29'. Aside port 45 in sleeve casing 43 and a similar port in alignmenttherewith in outer casing 42' are each fitted with a single or commonhose adapter 46 to which 4 hose 47 is removably attached. This putsannular space 39 in communication with an abrasive container laterreferred to.

it will thus be seen that there is provided a swivelable jointconnection between the separator chamber housing and blast head housing10' whereby the blast head can be rotated through 360 with respect tothe abrasive chamber, and that there are three concentric passagewaysthrough this swivel joint connection: an innermost passageway throughblast air tube 28 which communicates with the blast nozzle chamber 15',an outermost passageway 41 through which the separator chamber 48 is incommunication with the outer passageway 23 (i. e., the aforesaid outerchannel) in blast head 10, and an intermediate passageway 39 throughwhich hose 47 is in communication with eductor sleeve 16 and blast cone19 (i. e., the aforesaid inner channel) in blast head 10.

Abrasive container 49 (Fig. 2) fits against that part of the separatorhousing 42 which forms the main body of the separator chamber 48, with agasket 5 providing a seal between them. A screen 51 is positionedbetween the separator chamber and the abrasive container and is held inplace by having its edge secured underneath gasket 50. A circular baflleplate 52 is positioned a short distance above said screen and is securedthereto by screw bolt 53. The said bafile plate is of such diameter asto leave a circumferential space between it and the housing of separatorchamber 48. The abrasive container 49 is held in place by snap-overlatches 54, similar to suit-case latches, which hook over lugs 55protruding from housing 42, which turn on pins 56 and are operated bylevers 57. A small bleed hole 58, which may be about ,4 inch indiameter, is provided through the wallof abrasive container 49'near thebottom of the container. Abrasive hose 47 (Fig. 5-) which, as aforesaid,connects with the annular passageway in the aforesaid swivel jointconnection between separator chamber 48 and blast-head 10 fits tightlyover a spout 59 leading from near the bottom of abrasive container 49.It will thus be seen that a continuous passageway is provided fromabrasive container 49 through hose 47 and annular passageway 39 to thespace surrounding the exit path from blast nozzle 12 and thence-throughthe aforesaid inner channel of blast head 10.

As seen from Figs. 1 and 3 the main body of separator chamber 48enclosed by separator housing 42 is scroll shaped. As seen from Fig. 2the separator housing 42 is formed into an upwardly extending part whichoncloses a recess in the upper part of the separator chamber 48, theupper part of this recess being shown in the sectional view of Fig. 6. Atubular flanged elbow 60 (Figs. 1 and 2) is secured by bolts 61 to thatpart of the housing 42 which forms the said recess and is scaled theretoby O-ring 62 positioned in an appropriate groove in the housing 42. Apassageway means 63 (Figs. 6 and 2) extends inwardly from the housingadjoining the area of attachment of said flanged tubular elbow 60, anopening being formed in said housing whereby said tubular elbow is incommunication with said means. Suction nozzle 64 is threadedly engagedto the end of said means, a gasket 65 providing a seal. Suction tube 66is pressed or otherwise secured in an opening through the separatorchamber housing in line with said suction nozzle 64 whereby said nozzledischarges into said tube. The tube 66 in turn discharges into a dustbag 67 (partially shown in Fig. l) secured to a sleeve 68, preferably ofrubber, which in turn is suitably secured to tube 66 as by snapping itover beads 69 rolled into tube 66. Any appropri ate fastening orclamping means may be used to secure the dust bag whereby tube 66 maydischarge thereinto. The dust bag is preferably of a type similar tothat used on some vacuum cleaners and may be provided with appropriatemeans for emptying it. It will thus be seen that leading to the dust bag67 there is a continuous passageWay which leads from the annularpassageway 23,

surrounding and beginning at the exit end of blast cone 19, through theoutermost annular passageway" 41 thence through the scroll-shapedportion of separator chamber 48 to the entrance area of tube 66surrounding the exit end of exhaust nozzle 64 and thence through tube 66into dust bag 67.

Next will be described our improved valve mechanism which is anotherimportant feature of novelty in the operation of the foregoingapparatus.

A valve body 70 (Figs. 1, 2 and 6) having a longitudinal passageway 71'therethrough, is secured to elbow 60 in any suitable manner, a standardfiarcless tube type fitting being illustrated comprising union nut 72 inthreaded engagement with said valve body and provided with a radiallyextending shoulder on its outer end which in coaction with the end ofsaid body, said end being desirably beveled, compresses ferrules 73 and'74 to form a seal. If desired, valve body 70 and flanged elbow 6t maybe made of one continuous piece, without the necessity for any jointstructure therebetween. An annular shoulder 74 extending inwardly fromthe wall of said valve body in a plane oblique to the longitudinal axisof the valve body is adapted to seat primary valve 75 whereby saidpassageway 71 can be completely closed. A tubular branch 76 extendingfrom said valve body provides a brancn passageway 77 forwardly of andcoaxially with said valve seat and valve 75. A secondary valve 78 isadapted to seat upon an annular shoulder formed on the inside of tubularbranch 76 to completely close branch passageway 77, said secondary valve78 being preferably coaxial with primary valve 75. Valve stem 79, fitsthrough bushing 80 which threadedly engages a hollow cylindrical branch81 formed on valve body 7:9 in axial alignment with the branch 76, saidbushing being sealed by gasket washer 82s and said valve stem beingsealed by packing 33 held in place by spring 8 which pushes, againstwasher ds'contacting said packing and against washer 86 which backs upprimary valve 75, said spring 84 also tending to push said primary valveagainst its seat in the valve body. Said primary valve 75 is secured tothe said valve stem by nut 87 and washer 88. The secondary valve 78 issecured to a small bushing 89 which slides on the said valve stem. Thisvalve is backed up by washer 99 and is held against its seat bycompression spring 9i. ,At the lower end of the said valve stem, andspaced a short distance from the sliding bushing 89, a small snap ring92 on the valve stem acts as a shoulder adapted to contact said slidingbushing when said alve stem is moved a sufficient distance in anupwardly axial direction. it will thus be seen that in an axial upwardmovement of the valve stem a distance less than e distance between ring92, and bushing ti primary valve 75 will be lifted from its seat whilethe secondary valve will remain seated, thereby opening up a continuouspassageway through the longitudinal portion 71 of the valve body, thepassageway through the branch 76 remainin closed; also that upon.continuing the upward movement of the valve stem the secondary valve7iiwill then in turn be lifted from its seat so that an open passageway isthen provided outwardly through passageway 77 from passageway 71. itwill also be seen that upon a sufficient downward movement of the valvestem 7? secondry valve 78 will be seated a short interval of timeprimary valve 75 is seated, and that thus'the pass 77 is closed a shortinterval of time prior to the closing of the continuous passageway 71.

The said valve stem 79 is moved upwardly by valve handle lever 93 whichpivots on hinge 94 '(Figs. 1 and 2) appropriately positioned and securedvalve 60, the valve handle being pivotally connected to yoke 55 which issecured to the upper end of the valve stem 79 by lock nut 96 and washer97 (Fig. 6). An upward movement of lever93 transmits an axial upwardmove ment to the valve stem 7% lifting valves 75 and 78 successively inthe manner hereinabove explained. The

body

6 valve stem 79 will be moved downwardly automatically bythe action ofspring $4 upon the release of valve lever 93 so that the successiveclosing of valves 75 and 78 as above explained will be automatic.

A pipe nipple 98 screwed into the outer end of valve body 64 andthreaded to receive a compressed air hose (not shown) serves to conveycompressed air from any convenient source into the passageway 71 of thevalve body 70. The said pipe nipple, with the valve handle lever 93 inproximity thereto, also serves as a hand grip for actuating said valvehandle lever.

At the outer end of branch 76 of the said valve body, forwardly from thesecondary valve 78, a compressed air conduit 99 is connected thereto bya flareless tube nut lull and ferrules 101 and 102. in a manner similarto the connection of valve body 70 to flanged pipe 60 hereinbeforedescribed. This conduit 9 is connected to the compressed air hose 36which latter leads around the aforesaid scroll-shaped portion ofseparator chamber 48 into the aforesaid blast air tube It will be seenfrom the foregoing description that with pipe nipple 98 connected to asource of compressed air, when primary valve 75 is first opened,secondary valve 78 then remaining closed, compressed air will flowthrough the longitudinal passageway '71 of the valve body, thencethrough flanged elbow 60 and thence through suction nozzle 64 and bedischarged into tube 66 leading to dust bag 67. The suction effectcreated by the eductor action of exhaust nozzle 64 extends back throughthe scroll shaped portion of separator chamber 425, thence back throughthe outer annular passageway ll in the swivel connection of separatorchamber 48 to blast head housing 10, and thence back to the aforesaidinner channel in blast head 10. It will also be seen that when thesecondary valve '78 opens compressed air will flow from passageway Flthrough the branch passageway 76, through conduit 99 and compressed airhose 36 through blast air tube 28 into nozzle chamber 15 and thencethrough blast nozzle 12, discharging into eductcr sleeve 16 and blastcone l9 onto any surface against which the mouth piece 27 of blast head10 is placed. The suction created by the eductor action of blast nozzle12 will carry back through the inner annular space 39 surrounding blastair tube 28, thence back through conduit 47 to the bottom of abrasivecontainer 49, whereby abrasive material will be drawn from abrasivecontainer 49 and be caused to entrain with the blast air streamdischarged through the eductor sleeve 16 in the blast head. It will alsobe seen that in any cessation of operation of the blast cleaning machinethe blast air supply to blast nozzle 12 is automatically cut off beforethat .to exhaust nozzle 64 so that suction effect to remove spentabrasive and debris from the surface being cleaned automaticallycontinues for a brief period, thus avoiding any spattering of spentabrasive and debris and assuring freedom therefrom on the said surfacewhen the machine is removed. Likewise, upon beginning to clean a givensurface the suction effect of exhaust nozzle 64- starts prior to theblast action of nozzle 12. It will be further observed that when theoperator has moved the valve handle 93 to a position where valve 75 isopen while valve 78 remains closed, the said handle may be held in thatposition at the will of the operator during which time the suctioneffect and exhaust operation created by exhaust nozzle 64 is maintainedin the absence of any blast from blast nozzle l2. Advantage is taken ofthis to quickly load the rt-iachine with abrasive material by simplyplacing a desired supply of abrasive material on a surface and brin ingthe mouthpiece 27' of blast head it in contact with said supply whilesuch suction is in operation. Thus the machine can be loaded without thenecessity of opening the abrasive container of the machine.

It may be questioned whether by reason of the open communication betweenseparator chamber 48 and abra sive container {through screen 51) and the.factthat exhaust nozzle 64 is positioned down stream from the separatorchamber, the suction effect of the said exhaust nozzle may work againstthe suction effect of blast nozzle 12 and thereby adversely affect theflow of abrasive from the abrasive container. The equipment is designedso that the intensity of vacuum provided by the eductc-r action of theblast nozzle is much greater than the vacuum created by the eductoraction of the exhaust nozzle and experiments with our device have shownthat there is little or no difference in the effectiveness of the blastover that obtained in machines where the exhaust nozzle is up-streamwith reference to the separator chamber.

The baffle plate 52 (Fig. 2) positioned as foresaid between theseparator chamber and the abrasive container, serves to control anddirect the exhaust stream so as to carry the dust and light flakyparticles of debris away toward the tube 66 and into the dust bag, largeflakes of debris being held on screen 51 to prevent clogging of themachine while the abrasive material passes through the annular spaceabout the periphery of the baffle plate downwardly into abrasivecontainer 49.

By the incorporation of the features explained in the foregoingdescription, we have obtained a portable blast cleaning machine that iscompact, light in weight, easily carried about and operated by a singleperson. It is operated by gripping one hand on the valve handle lever 93and pipe nipple 98 which connects the machine with a single source ofcompressed air and holding the blast head with the other hand. Thedesign affords a n well balanced machine that is easy to hold. It isoperated with air pressure at from 80 to 120 p. s. i. The free swivelability of the blast head through a complete circle affords asyaccess to the many variously located surfaces encountered in blastcleaning work. The O-ring used in the swivel joint connection issumciently compressed in position to offer the required resistance toturning so that once the blast head is turned to the correct position itwill remain in that relative position for as long as desired. During theoperation the abrasive that is separated out from the suction stream bycen trifugal action falls outside the battle plate, through the screeninto the abrasive container. The baflie plate prevents the abrasive inthe container from being drawn out of the container into the exhauststream.

The lugs on the surface contacting boot act against any tendency for therubber boot to collapse against the surface when the machine is usedwith suction only whenever primary'valve 75 is lifted from its seatwhile secondary valve 755 still remains seated. Such lugs may i beprovided on the boot by other means than molding out of rubber, such asby using projecting rivet heads or special pins in the boot. The metalparts which are exposed to abrasion may be treated in any desirablemanner for abrasion resistance or they may be coated with lubber orother suitable material such as various coatings prepared fro; plasticsor plastic like substances. if desired, certain metal parts may beentirely substituted by molded rubber parts and the like; or moldedrubber construction may be used to form into one piece certain partsshown in the illustrated embodiment as comprised of separate pieces. Forexample in the blast head it. molded rubber construction may be employedwhile still preserving the inner and the outer channels therethrough.

While we have illustrated and described our invention in detail, it isunderstood that various modifications may be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention as defined in the appended claims.

We claim:

1. In a portable abrasive blast cleaning machine to be carried andoperated by a single operator for removing debris from a coated surface,said machine including an 8 blast cleaned, an inner and an outer casingspaced apart to form an inner channel for the passage of abrasive towardsaid surface and an outer channel for the passage of spent abrasive anddebris from said surface, a blast nozzle adapted to discharge a blaststream of air into said inner channel and against said area, a separatorchamber wherein spent abrasive is separated from debris and dust, anexhaust nozzle adapted to create suction in said outer channel of saidblast head, passageway connecting means to provide, when said contactorboot is in contact withsaid surface, a short, endless and always openrecirculatory path for abrasive material from said abrasive container tosaid blast head and against said surface, thence to said separatorchamber and back to said container, the combination therewith of aswivel joint means connecting said blast head to said separator chamberto permit rotation of said head with respect to said separator'chamberwherein the longitudinal axis of said head may move through 360 in aplane perpendicular to the axis of rotation, said swivel joint meanscomprising an inner and an outer casing spaced apart and extendinglaterally from said blast head rotatably connected, respectively, to aninner and an outer casing spaced apart and extending laterally from saidseparator chamber, the space enclosed between said inner and outerconnected casings constituting a passageway communicating between saidouter channel of said blast head and the said separator chamber,passageway means, positioned within the space enclosed by said innerconnected abrasive container, a blast head having a surface con-.3

tactor boot adapted to contact an area of surface to be casings but outof communication with said space, adapted to convey compressed air tosaid blast nozzle; the remaining portion of said space enclosed by saidinner connected casings constituting a passageway through which abrasivematerial passes enroute from said abrasive container to said blast head.

2. A portable blast cleaning machine in accordance with claim 1 whereinsaid exhaust nozzle is so positioned that its zone of eduction is incommunication with said separator chamber whereby dust separated fromspent abrasive in said separator chamber is entrained with the exit airfrom said exhaust nozzle, and a dust bag adapted to receive thedischarge from said exhaust nozzle.

3. A portable blast cleaning machine in accordance with claim 2, whereinsaid separator chamber presents a scroll-shaped path leading from thespace in said swivel joint connecting means between said inner and outerconnected casings, but otherwise being circular in crosssection; saidabrasive container being downwardly directed from said separator chamberand fitted circumferentially to the lower end thereof; and a circularbaffle plate positioned between said separator chamber and said abrasivecontainer having a diameter less than that of said separator chamber toprovide a circumferential, ringlike space between said baflle plate andthe wall of said separator chamber.

4. In a portable blast cleaning machine in accordance with claim 1, thecombination therewith of a valve mechanism to control the air flow froma single source of compressed air supply to both said blast nozzle andsaid exhaust nozzle, comprising a valve body, a primary passagewaytherethrough adapted to lead from said single source of compressed airto supply air to said exhaust nozzle, a secondary passageway branchingfrom said primary passageway to supply air to said blast nozzle, aprimary valve positioned upstream from said branch passageway, adaptedto close said primary passageway, a secondary valve adapted to closesaid branch passageway, a single and manually operated actuating meansassociated with both said valves adapted to open said primary valve inadvance of said secondary valve, and separate spring actuating meansadapted automatically to close said secondary valve in advance of saidprimary valve upon release of said manually operated actuating means.

5. A portable blast cleaning machine in accordance with claim 4, whereinsaid exhaust nozzle is so positioned 9 that its zone of eduction is incommunication with said separator chamber whereby dust separated-fromspent abrasive in said separator chamber is entrained with the exit airfrom said exhaust nozzle, and a dust bag adapted to receive thedischarge from said exhaust nozzle.

6. A portable 'blast cleaning machine in accordance with claim 4,wherein said separator chamber presents a scroll-shaped path leadingfrom-the space in said swivel joint connecting means between said innerand outer connected casings, but otherwise being circular incrosssection; said abrasive container being downwardly directed fromsaid separator chamber and fitted circumferentially to the lower endthereof; and a circular bafiie plate positioned between said separatorchamber and said abrasive container having a diameter less than that ofsaid separator chamber to provide a circumferential, ring-like spacebetween said bafiie plate and the wall of said separator chamber.

7. in a portable abrasive blast cleaning machine to be carried andoperated by a single operator for removing debris from a coated surface,said machine including an abrasive container, a blast head havingasurface contactor boot adapted to contact an area of surface to beblast cleaned, an inner and an outer casing spaced apart to form aninner channel for the passage of abrasive toward said surface and anouter channel for the passage of spent abrasive and debris from saidsurface, a blast nozzle adapted to discharge a blast stream'of air intosaid inner channel and against said area, a separator chamber whereinspent abrasive is separated from debris and dust, an exhaust nozzleadapted to create suction in said outer channel of said blast head,passageway connecting means to provide, when said contactor boot is incontact with said surface, a short, endless and always openrecirculatory path for abrasive material from said abrasive container tosaid blast head and against said surface, thence to said separatorchamber andback to said container, .the improvement consisting of swiveljoint connecting means between said blast head and said separatorchamber comprising an outer and an inner casing spaced apart andprojecting from said blast head laterally with respect to itslongitudinal axis and having coaxial circumferential end portions toform an inner, and an outer concentric space which spaces communicaterespectively with said bers, respectively, of said circumferential endportions of said laterally extending casings of said blast head, theouter concentric space formed by said casings of said separator chamberbeing in communication withkthe 'interior of said separator chamber andthe inner of said concentric spaces being dead ended in the direction ofsaid separator chamber, means by which said complemental mating membersare sealably and constrainedly rotatably connected with their respectivecounterpart'circumferential end portions of said externally extendingcasings of said blast head whereby said two outer and said two innerconcentric spaces are formed into one outer and one inner concentricspace, a side port in the inner, and a side port in the outer of saidtwo laterally extending casings of said separator chamber, a conduitmeans having one end sealably fitted in the said side port of said innercasing and passing through and sealably fitted in said side port of saidouter casing and the other end of said conduit means communicating withsaid abrasive container to constitute a passageway from .said abrasivecontainer into said inner concentric space, a first axial portpositioned axially and inwardly with respect to said inner casing ofsaid separator chamber and extending through its housing structure tothe exterior thereof, a second axial port positioned axially and"inwardly with .respect to said inner circumferentially ended casing of.said blasthead and extending through thehousing structure thereof to theentrance to said blast nozzle, a pipe having one end -fitted in saidsecond axial port extending through and fitted in said first axial port,at least one of said fittings being alsorotatably fitted, to constitutea part of said swivelable joint connection and to form with said totatably connected inner casings a third concentric passageway throughsaid swivel joint.

8. In a portable blast cleaning machine in accordance with claim 7, thecombination therewith of a valve mechanism to control the air flow froma single source of compressed air supply to both said blast nozzle andsaid exhaust-nozzle, comprising a valve body, a primary passageway'therethrough adapted to lead from said single source of compressed airtosupply air to said exhaust nozzle, a secondary passageway branchingfrom said primary passageway 'to supply air to said blast nozzle, 2.primary'valve positioned upstream from said branch passageway adapted toclose said primary passageway,

a secondary valve adapted to' close said branch passageway, a single andmanually operated actuating means associated with-both said valvesadapted to open said primary valve in advance of said secondary valve,and separate spring actuating means adapted automatically to close saidsecondary valve in advance of said primary valve upon release of saidmanually operated actuating means.

9. A portable blast cleaning machine in accordance with claim 8, whereinsaidexhaust nozzle is so positioned that its zone of eduction is incommunication with said separator chamber 'wherebydust separated fromspent abrasive in said separator chamber is entrained with the exit airfrom 'said'exhaustnozzle, and a dust bag adapted to receive thedischarge'from said exhaust nozzle.

10. Ina portable abrasive blast cleaning machine of the type referred toin claim 1, the improvement consisting of a'swivel joint connectingmeans between said blast head and-said separator chamber comprising aninner and an outer casing-spaced apart and extending laterally from saidblast head and adapted to be rotatably connected to an inner and anouter casing spaced apart and extending laterally from said separatorchamber, means to rotatably connect said twoinner and said'two outercasings, respectively, to constitute thereof a 'swiveljoint and to formtherein two concentric passageways, the outer of said passagewayscommunicating withsaid outer channel of said blast head and saidseparator chamber and the inne ofsaid passageways communicating in onedirection with said inner channel of said blast head, a pipe axially andinwardly positioned with respect to said inner connected casings to formwith reference thereto a third concentric passageway, a port'in thehousing, structure of said blast head leading to the entrance to saidblast nozzle and in which port one end of said pipe is sealablyfitted, aport in the housing structure of said separator chamber leading to theexterior of said separator chamber and through which port-said pipeextends and is sealably and rotatably 'fittedtherein, a side port in"each' of said two laterally extending casings of said separator chamber,and a single conduit means which leads from said abrasive containerfitted in both said side ports to bring said abrasive container intocommunication with the intermediate of said three concentricpassageways.

11. In axportable blast cleaning machine in accordance with claim 10,the combination therewith of a valve mechanism to control the: airflowfrom a single source of compressed air supply to both said blastnozzle and said exhaustnozzle, comprising a valve body, a primarypassageway therethrough'adapted to'lead from said single source ofcompressedxairto .supply air to said exhaust nozzle, asecondarypassageway branching from said primary passageway to supplyair to saidblast nozzle, a primary valve positionedupstream from said branchpassageway adapted ,toyclose said primary passageway, a

secondary valve adapted to close said branch passage 11 way, a singleand manually operated actuating means associated with both said valvesadapted to open said primary valve in advance of said secondary valve,and separate spring actuating means adapted automatically to close saidsecondary valve in advance of said primary valve upon release of saidmanually operated actuating means.

12. A portable blast cleaning machine in accordance with claim 11wherein said exhaust nozzle is so positioned that its zone of eductionis in communication with said separator chamber whereby dust separatedfrom spent abrasive in said separator chamber is entrained with the exitair from said exhaust nozzle, and a dust bag adapted to receive thedischarge from said exhaust nozzle.

13. A portable blast cleaning machine in accordance with claim 11wherein said separator chamber presents a scroll-shaped path leadingfrom the space in said swivel joint connecting means between said innerand outer connected casings, but otherwise being circular incrosssection; said abrasive container being downwardly directed fromsaid separator chamber and fitted circumferentially to the lower endthereof; and a circular bafile plate positioned between said separatorchamber and said abrasive container having a diameter less than that ofsaid separator chamber to provide a circumferential, ring-like spacebetween said bafile plate and the wall of said separator chamber.

l4. ln a portable abrasive blast cleaning machine to be carried andoperated by a single operator for removing debris from a coated surface,said machine including an abrasive container, a blast head having asurface contactor boot adapted to contact an area of surface to be blastcleaned, an inner and an outer casing spaced apart to form an innerchannel for the passage of abrasive toward said surface and an outerchannel for the passage of spent abrasive and debris from said surface,a blast nozzle adapted to discharge a blast stream of air into saidinner channel and against said area, a separator chamber wherein spentabrasive is separated from debris and dust, an exhaust nozzle adapted tocreate suction in said outer channel of said blast head, passagewayconnecting means to provide, when said contactor boot is in contact withsaid surface, a'short, endless and always open recirculatory path forabrasive material from said abrasive container to said blast head andagainst said surface, thence to said separator chamber and back to saidcontainer, the improvement comprising a swivel joint means connectingsaid blast head to said separator chamber to permit rotation of saidblast head with respect to said separator chamber, and means providingseparate passageways through said swivel joint means for the passage ofcompressed air to said blast nozzle, abrasive material to said innerchannel of said blast head, and spent abrasive and debris from saidouter channel of said blast head to said separator chamber.

15. In a portable blast cleaning machine in accordance with claim 14,the combination therewith of a valve mechanism to control the air fiowfrom a single source of compressed air supply to both said blast nozzleand said exhaust nozzle, comprising a valve body, a primary passagewaytherethrough adapted 'to lead from said single source of compressed airto supply air to said exhaust nozzle, a secondary passageway branchingfrom said primary passageway to supply air to said blast nozzle, aprimary valve positioned upstream from said branch passageway adapted toclose said primary passageway, a secondary valve adapted to close saidbranch passageway, a single and manually operated actuating meansassociated with both said valves adapted to open said primary valve inadvance of said secondary valve, and separate spring actuating meansadapted automatically to close said secondary valve in advance of saidprimary valve upon release'of said manually operated actuating 16. In aportable abrasive blast cleaning machine to i be carried and operated bya single operator, said machine including an abrasive container, a blasthead having an inner channel for the passage of abrasive toward asurface to be cleaned and an outer channel for the passage of spentabrasive and debris from said surface, a surface contactor boot on saidblast head adapted to contact a surface to be blast cleaned, a blastnozzle to discharge a blast stream into and against said surface, aseparator chamber wherein spent abrasive is separated from debris anddust, an exhaust nozzle adapted to create suction in said outer channelof said blast head, and passageway connecting means to provide, whensaid contactor boot is in contact with said surface and the machine isconnected with a single source of compressed air, a short, endless andalways open recirculatory path for abrasive material from said abrasivecontainer to said blast head and against said surface, thence to saidseparator chamber and back to said container, the improvement comprisinga swivel joint means connecting said blast head to said separatorchamber adapted to rotate through 360 and having three concentricpassageways therethrough, the outermost of said passagewayscommunicating between said outer channel of said blast head and saidseparator chamber, the intermediate of said passageways communicatingbetween a conduit which leads from said abrasive container and saidinner channel of said blast head, and the innermost of said passagewayscommunicating between a source of compressed air and the entrance tosaid blast nozzle, said swivel joint means comprising an inner and anouter casing spaced apart, extending laterally from said blast head andterminating circumferentially and concentrically and adapted to materespectively with an inner and an outer circumferentially concentricallyterminating casing projecting laterally from said separator chamber,means for rotatably and sealably 1 connecting said mating casings attheir circumferential terminal ends, the outer concentric space therebyformed constituting the outermost of said three concentric passageways,a first axial port through the housing of said separator chamber and asecond axial port through the housing of said blast head, both saidports being axially positioned with reference to' said mated andconnected casings, and communicating with the space enclosed by the saidinner mated casings, the said first axial port communicating also withthe space outside of said separator chamber and the said second axialport communicating also with the entrance to said blast nozzle in saidblast head, a pipe having one end sealably fitted in said second axialport and extending through and fitted in said first axial port, therebydividing the space enclosed by said inner mated casings into theintermediate and the innermost of said three concentric passageways,said pipe being also rotatably fitted in at least one of said axialports, means for connecting the end of said pipe extending outwardlythrough said first axial port with a source of compressed air, wherebycompressed air may pass through the innermost of said three concentricpassageways to said blast nozzle, a side port in the inner, and a sideport in the outer of said two laterally extending casings of saidseparator chamber, a conduit means having one end sealably fitted in thesaid side port of said inner casing and passing through and sealablyfitted in said side port of said outer casing and the other end of saidconduit means communicating with said abrasive container to form apassagewayfrom said abrasive container into said intermediate of saidthree concentric passageways.

and dust, a blast nozzle to discharge a blast stream of air into saidfirst channel against said surface and adapted to create suction on saidabrasive container and to effect entrainment of abrasive from saidabrasive container into said blast stream, and an exhaust nozzle adaptedto create suction in said second channel and effect entrainment ofmaterial from said second channel into its discharging air stream, theimprovement comprising a swivel joint means connecting said blast headto said separator chamber to permit rotation of said blast head withrespect to said separator chamber, a compressed air conduit axiallypositioned in said swivel joint means and communicating with said blastnozzle, and means constituting two separate passageways through saidjoint means positioned concentric to said compressed air conduit, thefirst for the passage of abrasive material enroute from said abrasivecontainer to said first channel in said blast head and the second forthe passage of spent abrasive and debris en route from said secondchannel of said blast head to said separator chamber.

18. A portable blast cleaning machine in accordance with claim 17wherein said exhaust nozzle is so positioned that its zone ofentrainment is in communication with said separator chamber to pullsuction thereon and separate dust from spent abrasive for entrainment ofsaid dust into the discharging air stream from said suction nozzle, saidseparator chamber having a scroll-shaped path leading from the saidsecond concentric passageway of said swivel joint means but otherwisebeing circular in cross-section, said abrasive container beingdownwardly directed from said separator chamber and fitted circumferentially to the lower end thereof, and a circular bafile platepositioned between said separator chamber and said abrasive containerhaving a diameter less than that of said separator chamber to provide acircular, ring-like space between said baflle plate and the wall of saidseparator chamber.

19. In an abrasive blast cleaning machine having a blast head providedwith a first channel through which a blast air stream carrying abrasivematerial is directed toward a work surface and a second channel throughwhich a suction air stream draws spent abrasive and debris away fromsaid surface, the combination therewith 3 adapted to close said branchpassageway, a first actuating means associated with both said valvesadapted to open said primary valve in advance of said secondary valve,and a second actuating means adapted automatically to close saidsecondary valve in advance or" said primary valve upon release of saidfirst actuating means.

20. In an abrasive blast cleaning machine having a blast head adapted tocontact an area of surface to be cleaned, a blast nozzle in said blasthead to direct a stream of air and abrasive against said area, a firstpassageway into said blast head to convey compressed air thereinto forsaid blast nozzle, a second passageway into said blast head to conveythereinto abrasive for the abrasive component of said stream of air andabrasive, a separator chamber wherein spent abrasive is separated fromdebris and dust, and a third passageway, leading from said blast head,to convey spent abrasive and debris from said area to said separatorchamber, the improvement comprising a swivel joint means connecting saidblast head to said separator chamber to permit rotation of said blasthead with respect to said separator chamber, and means providingseparate passageways through said swivel joint means for the passage ofcompressed air to said first passageway, abrasive material to saidsecond passageway, and spent abrasive and debris from said thirdpassageway.

References Cited in the file of this patent UNITED STATES PATENTS2,455,514 Mead Dec. 7, 1948 2,479,299 Biggs Aug. 16, 1949 2,599,997Iannelli June 10, 1952 2,723,498 Hastrup et al. Nov. 15, 1955

